Interaction between the H ii region and AFGL 333-Ridge: Implications for the star formation scenario

Abstract

We investigated the star formation activities in the AFGL 333 region, which is in the vicinity of the W4 expanding bubble, by conducting NH 3 (1,1), (2,2), and (3,3) mapping observations with the 45 m Nobeyama Radio Telescope at an angular resolution of 75 ′′ . The morphology of the NH 3 (1,1) map shows a bow-shape structure with the size of 2.0 × 0.6 pc as seen in the dust continuum. At the interface between the W4 bubble and the dense NH 3 cloud, the compact HII region G 134.2+0.8, associated with IRAS 02245+6115, is located. Interestingly, just north and south of G 134.2+0.8 we found NH 3 emission exhibiting large velocity widths of ∼ 2.8 km s −1 , compared to 1.8 km s −1 at the other positions. As the possibility of mechanical energy injection through the activity of YSO(s) is low, we considered the origin of the large turbulent gas motion as indication of interaction between the compact HII region and the periphery of the dense molecular cloud. We also found expanding motion of the CO emission associated with G 134.2+0.8. The overall structure of the AFGL 333-Ridge might have been formed by the expanding bubble of W4. However, the small velocity widths observed west of IRAS 02245+6115, around the center of the dense molecular cloud, suggest that interaction with the compact HII region is limited. Therefore the YSOs (dominantly Class 0/I) in the core of the AFGL 333-Ridge dense molecular cloud most likely formed in quiescent mode. As has been previously suggested for the large scale star formation in the W3 giant molecular cloud, our results show an apparent coexistence of induced and quiescent star formation in this region. It appears that star formation in the AFGL 333 region has proceeded without significant external triggers, but accompanying stellar feedback environment.

A Faraday Rotation Study of the Stellar Bubble and H ii Region Associated with the W4 Complex

“…Moore et al (2007) similarly conclude that the W3 molecular cloud has been compressed on one side by the expansion of IC 1805. While infrared sources nestled between the western edge of IC 1805 and eastern edge of the W3 molecular cloud are thought to be the product of this interaction , W3 Main, W3 (OH), and W3 North are thought to be sites of triggered star formation from IC 1795, which is part of W3 as well and not from the expansions of the ionization front (Nakano et al 2017;Jose et al 2016;Kiminki et al 2015). There is therefore uncertainty regarding a physical connection between W3 and IC 1805.…”

CO Outflow Candidates toward the W3/4/5 Complex I: The Sample and Its Spatial Distribution

“…In AFGL 333, outflow candidate 115 was associated with an outflow identified from the CO (2 → 1) line and an H 2 O maser (see Nakano et al 2017). They also suggested that star formation in the AFGL 333 region proceeded without significant external triggers.…”

A Kinematic Analysis of the Giant Molecular Complex W3; Possible Evidence for Cloud-Cloud Collisions that Triggered OB Star Clusters in W3 Main and W3(OH)

“…The AFGL 333 region was investigated by Nakano et al (2017); Liang et al (2021) and will not be dealt with in the present paper. This paper is organized as follows; Section 2 describes the datasets employed and Section 3 gives the results of the present kinematical analysis.…”